Who gets soy allergy?
Although soy allergy occurs most often in infants and children, it can appear at any age and can be caused by foods that had been previously eaten without any problems. Many infants can lose their allergy as they grow older.
Soybeans are legumes. Other foods in the legume family include peanut, navy beans, kidney beans, lima beans, string beans, pinto beans, chickpeas (garbanzo beans), lentils, peas, black-eyed peas, and licorice. Some people with soy allergy may have a reaction after eating other legumes. If you have soy allergy, you should talk with your doctor about what other legumes you might need to avoid.
Symptoms and Causes
What are the symptoms of soy allergy?
Allergic reactions to foods usually begin within minutes to a few hours after eating the food. The severity of symptoms can vary widely from one person to another. Mildly allergic persons may have itching and a few hives, while severely allergic persons may experience severe, life-threatening symptoms such as breathing problems or swelling of the throat. The symptoms of a food allergy may include any or several of the following:
- Tingling or swelling of the lips, tongue, or throat.
- Chest tightness, shortness of breath, or difficulty breathing.
- Abdominal pain.
- Nausea, vomiting, or diarrhea.
- Anaphylaxis: sudden, severe, potentially fatal, systemic allergic reaction that can involve several areas of the body.
Diagnosis and Tests
How is soy allergy diagnosed?
Your healthcare provider will examine you after asking for a medical history. You might be asked to keep track of your food and any symptoms you might have.
There are other tests for soy allergy. They are:
- A blood test: A blood sample will be tested for immunoglobulin E (IgE) antibodies to soy. This may indicate an allergy.
- A skin-prick test: A drop or two of liquid composed of soy protein is put on your back or on your forearm. A sterile probe pokes the area which lets the liquid get into the skin. If your skin produces a red bump in about 15 minutes, you might be allergic.
- An oral food challenge: You will be asked to eat some type of soy food item. This will happen at the doctor’s office or a special food challenge center with medication and emergency equipment ready to deal with any reaction.
Management and Treatment
How is soy allergy treated?
If you have soy allergy, strict avoidance of soy is the only way to prevent a reaction. Your doctor might suggest antihistamines or injectable epinephrine for treating reactions.
Avoiding products made with soy is difficult because soy is contained in many processed food products. The Food and Drug Administration (FDA) requires food manufacturers to list common food allergens on food labels in plain terms to make it easier to identify the food allergens. Food labels must clearly list eight allergens which account for almost 90 percent of all food allergies: cow’s milk, soy, wheat, egg, peanut, tree nuts, fish, and shellfish. Generally, soy lecithin and soy oil are tolerated by soy allergic individuals.
How can I best manage living with a soy allergy?
- Always know what you are eating and drinking.
- Always check the label ingredients before you use a product, even if the food was safe the last time you ate it. Manufacturers can change recipes and a soy-containing food may be added to the recipe.
- Teach children with soy allergy not to accept food from classmates or friends.
- When dining out, ask detailed questions about ingredients and how the food was prepared.
- Wear a medical alert bracelet with information about your allergy or carry an alert card with you.
- Talk with your doctor about how to prepare for a reaction. Mild reactions may be treated with oral antihistamines. Your doctor may prescribe self-injectable epinephrine to carry with you at all times in case you have a severe reaction.
How can I find out if soy is in a food product?
All FDA-regulated manufactured food products that contain as an ingredient a “major food allergen” (milk, wheat, egg, peanut, tree nuts, fish, crustacean shellfish, and soy) are required by U.S. law to list that allergen on the product label. For tree nuts, fish, and crustacean shellfish, the specific type of nut or fish must be listed. (Food Allergy Labeling and Consumer Protection Act, effective 1/2006.)
This guide provides information on how you can select soy-free foods by properly reading Nutrition Facts food labels. A Registered Dietitian can provide detailed nutrition education to help you develop a personal action plan.
A soy-free diet is indicated for soy protein allergy. The common allergens are listed either within the ingredient list or after the list. For example, if a product contains natto, a food made with fermented soybean, the product's label should list the term “soy” either after the term natto, or state “contains soy” after the list of ingredients. The FDA currently does not require manufacturers to state if the food was processed in a facility that also processes the 8 common food allergens.
Anyone allergic to soy should avoid the following ingredients and foods:
- Soy: in all forms, including soy flour, soy fiber, soy albumin, soy grits.
- Soy milk, soy ice cream, soy cheese, soy yogurt.
- Soybean (curd and granules).
- Soy protein (concentrate, isolate, hydrolyzed).
- Soy nuts and soy sprouts.
- Soy sauce and shoyu sauce.
- Tofu and textured vegetable protein (TVP).
You might want to avoid or be mindful when considering the following:
- Certain foods that may contain soy protein include Asian cuisine or foods that contain natural and artificial flavoring, vegetable broth, vegetable gum, or vegetable starch.
- Be cautious or avoid items labeled as hydrolyzed plant protein, hydrolyzed vegetable protein, protein extender, and protein filler.
- Soy has been found in things like vodka, alternative nut butters, ice cream, baby food, and low-fat peanut butter.
Studies have shown that most people with soy allergy can safely eat foods containing soy lecithin and soybean oil. The oil should not be cold-pressed, expeller-pressed, or extruded.